Re: crash in tmpfs_itimes since vmlocking2 merge

[Antti Kantee <pooka%cs.hut.fi@localhost>]

On Wed Jan 23 2008 at 12:49:09 -0800, Bill Stouder-Studenmund wrote:
> > This is the problem of forcibly unmounting a file system with device
> > vnodes on it.  There was a small discussion about splitting specfs
> > into two layers: one for the "host" file system (tmpfs in this case)
> > and one for the actual device info (specfs).  Then you could rip the
> > "host" part out without affecting the device part before the device goes
> > inactive and can be safely put to rest.
> 
> I'd actually say this is a bug in deadfs or tmpfs. Since we know the
> vnode's still in use, we should leave one around that doesn't cause the 
> kernel to crash.

We don't make device vnodes deadfs so that they would still work.  And I
don't think teaching every file system to operate without its backing data
structures is very feasible.  Hence, split it into two pieces so we don't
have to worry about it: the "frontend" (.e.g tmpfs) is deadfs'd while the
"backend" (specfs) continues operation until refcount drops to 0.

-- 
Antti Kantee <pooka%iki.fi@localhost>                     Of course he runs 
NetBSD
http://www.iki.fi/pooka/                          http://www.NetBSD.org/
    "la qualité la plus indispensable du cuisinier est l'exactitude"